What happens in the brain during depression?

Depression is not a bad mood. It is a biological reality and a medical condition, and when we talk about it as anything less than that, we belittle the people suffering from it.

It is important to remember that depression is a disease with a biological basis, along with psychological and social implications. It’s not simply a weakness that somebody should get over, or even something we have a say in.

If we’re being totally honest, the people who fight depression and its symptoms sounds like the opposite of weak. That kind of fight takes major strength.

Depression is a mood disorder that affects the way you think, feel, and behave. It causes feelings of sadness or hopelessness that can last anywhere from a few days to a few years. This is different than being upset about a minor setback or disappointment in your day.

Some people may experience mild depression only once in their lives, while others have several severe episodes over their lifetime. This more serious, long-lasting and intense form of depression is known as major depressive disorder (MDD). It may also be referred to as clinical depression or major depression.

The symptoms of MDD significantly interfere with daily activities, such school, work, and social events. They also impact mood and behavior as well as various physical functions, such as sleep and appetite. To be diagnosed with MDD, you must display five or more of the following symptoms at least once a day over the course of two weeks:

persistent feelings of sadness and hopelessness

lack of interest in doing most activities, including those you once enjoyed

decrease or increase in appetite accompanied by extreme weight loss or weight gain

sleeping too much or too little

restlessness

fatigue

excessive or inappropriate feelings of guilt or worthlessness

difficulty making decisions, thinking, and concentrating

multiple thoughts of death or suicide

a suicide attempt

People of any age may develop MDD, but the average age of onset is 32. According to the Depression and Bipolar Support Alliance, approximately 14.8 million American adults, or 6.7 percent of the United States population over age 18, are affected by MDD every year. The disorder also occurs in about one in 33 children and one in eight teens. In both children and adults, MDD may be treated with psychological counseling, antidepressant medication, or a combination of both therapies.

Researchers don’t know exactly why some people develop MDD, but they believe the following factors may play a role:

genetics: It appears that people with a family history of MDD are more likely to develop the disorder than others.

stress: A stressful life event, such a divorce or death of a loved one, can trigger an episode of MDD.

biochemical reactions: Chemicals in the brains of people with MDD seem to function differently than those in the brains of those without the disorder.

hormone imbalances: Changes in the balance of hormones may trigger MDD in certain people, especially during menopause or during and after pregnancy.

How Does Depression Affect the Brain?

There are three parts of the brain that appear to play a role in MDD: the hippocampus, amygdala, and prefrontal cortex.

The hippocampus is located near the center of the brain. It stores memories and regulates the production of a hormone called cortisol. The body releases cortisol during times of physical and mental stress, including during times of depression. Problems can occur when excessive amounts of cortisol are sent to the brain due to a stressful event or a chemical imbalance in the body. In a healthy brain, brain cells (neurons) are produced throughout a person’s adult life in a part of the hippocampuscalled the dentate gyrus. In people with MDD, however, the long-term exposure to increased cortisol levels can slow the production of new neurons and cause the neurons in the hippocampus to shrink. This can lead to memory problems.

The prefrontal cortex is located in the very front of the brain. It is responsible for regulating emotions, making decisions, and forming memories. When the body produces an excess amount of cortisol, the prefrontal cortex also appears to shrink.

The amygdala is the part of the brain that facilitates emotional responses, such as pleasure and fear. In people with MDD, the amygdala becomes enlarged and more active as a result of constant exposure to high levels of cortisol. An enlarged and hyperactive amygdala, along with abnormal activity in other parts of the brain, can result in disturbances in sleep and activity patterns. It can also cause the body to release irregular amounts of hormones and other chemicals in the body, leading to further complications.

Many researchers believe high cortisol levels play the biggest role in changing the physical structure and chemical activities of the brain, triggering the onset of MDD. Normally, cortisol levels are highest in the morning and decrease at night. In people with MDD, however, cortisol levels are always elevated, even at night.